In recent years, integrated circuits using an SOI (silicon on insulator) substrate that includes a thin single crystal silicon layer formed on an insulating surface have been developed instead of those using a bulk silicon wafer. The characteristics of the thin single crystal silicon layer formed on the insulating surface make it possible to completely separate transistors formed in the integrated circuit from each other. Further, since fully-depleted transistors can be formed, a semiconductor integrated circuit with high added values such as high integration, high speed driving, and low power consumption can be realized.
As a method for manufacturing an SOI substrate, a hydrogen ion implantation separation method is known. The hydrogen ion implantation separation method is a method by which a single crystal silicon layer is obtained in the following manner: a single crystal silicon substrate (a bond substrate) into which hydrogen ions are implanted is bonded to another substrate (a base substrate) with an insulating layer interposed between the substrates, and then the single crystal silicon substrate (the bond substrate) is separated along an ion implantation region by heat treatment. With the above hydrogen ion implantation separation method, an SOI substrate in which a single crystal silicon layer is provided over an insulating substrate such as a glass substrate can be manufactured (see Patent Document 1 as an example).